Concrete column and tube calculator
For deck footings, piers and round columns poured in cardboard form tubes. Enter the tube diameter, height and how many you’re pouring.
Concrete needed
3.3 cubic feet
- 80 lb bags
- 6 bags
- 60 lb bags
- 8 bags
- 40 lb bags
- 11 bags
- Cubic yards
- 0.12 yd³
How it works
A column is a cylinder. Its volume is π × radius² × height, with the radius being half the diameter, converted to feet. Bag counts use standard premix yields: 0.6 cubic feet for an 80 lb bag, 0.45 for 60 lb and 0.3 for 40 lb.
Example
With tube diameter 12 in, height 4 ft, number of columns 1, extra 5%, the answer is 3.3 cubic feet.
Tips before you buy
- Common form tube sizes are 8, 10, 12 and 14 inches. Bigger loads or poor soil call for a wider tube, or a flared footing base.
- Footings usually need to reach below the frost line where you live. Your building department can tell you the depth.
- Rod or tap the tube as you fill it to work out air pockets.
Common questions
How many bags of concrete for a 12 inch Sonotube 4 feet tall?
About 3.14 cubic feet, which is 6 bags of 80 lb mix.
How many bags for a 10 inch tube per foot of height?
About 0.55 cubic feet per foot, so roughly 1 bag of 80 lb mix per foot.
How much concrete is in a 12 inch tube per foot?
About 0.79 cubic feet per foot of height.